We reconsider a string theoretic inflationary model, where inflation is driven by $n$ multiple coincident $D3$-branes in the finite $n$ limit. We show that the finite $n$ action can be continued to the limit of large $n$, where it converges to the action for a wrapped $D5$-brane with $n$ units of U(1) flux. This provides an important consistency check of the scenario and allows for more control over certain back-reaction effects. We determine the most general form of the action for a specific sub-class of models and examine the non-relativistic limits of the theory where the branes move at speeds much less than the speed of light. The non-Abelian nature of the world-volume theory implies that the inflaton field is matrix valued and this results in modifications to the slow-roll parameters and Hubble-flow equations. A specific small field model of inflation is investigated where the branes move out of an AdS throat, and observational constraints are employed to place bounds on the background fluxes.
将慢卷情形和超相对论性卷的Dirac Born Infeld情形（其中，由于翘曲因子，即使具有超相对论性洛伦兹因子，暴胀子也缓慢移动）联系起来，我们发现KKLMMT D3/反D3膜暴胀是鲁棒的，也就是说，足够的暴胀e折叠在模型的参数空间中是相当普遍的。我们表明，相对论滚转的中间制度可以是相当有趣的观测。通过引入适当的暴胀参数，我们探索了参数空间，并给出了这种情况下宇宙学观测量的约束和预言。在其他性质中，这种情况允许张量/标量比r（在中间区域）或非高斯性f_NL（在超相对论区域）的当前观测界限饱和，但不是两者都饱和。
q-Deformation of the AdS5 x S5 Superstring S-matrix and its Relativistic Limit
基于中心扩张超代数su（2）的量子群变形的R-矩阵，定义了基本粒子多重态的四个可分解的非相对论S-矩阵|2）。S矩阵是两个独立耦合g和q=exp（iπ/k）的函数。主要结果是找到标量因子或修整相位，以确保满足么正性和交叉方程。对于一般的（g，k），S-矩阵是在快度环面的乘积上的分支函数。在极限k->无穷大时，其中一个与描述AdS 5 x S5弦世界片上磁振子激发的S矩阵相同，而另一个是TBA所需的镜像S矩阵。在g->无穷大极限，快度环退化，分支点消失，S-矩阵成为亚纯函数，这是相对论S-矩阵理论所要求的。然而，只有镜像S-矩阵满足正确的相对论交叉方程。在相对论极限下的镜像S-矩阵与半对称空间sine-Gordon理论的S-矩阵密切相关，但它是反对称的，而不是对称的束缚态。半对称空间sine-Gordon理论是由弦论通过Pohlmeyer约化得到的。插值S-矩阵在量子水平上实现了这样一个事实，即在经典水平上，这两个理论对应于同一可积系统的单参数辛结构族的不同极限。
We derive a new soft theorem that corresponds to the spontaneous breaking of Lorentz boosts. This is motivated by the dynamics of inflation in the sub-horizon (flat-space) limit, where spacetime becomes flat but Lorentz boosts are still broken. In this limit, the scattering amplitudes become sensible observables. We relate the soft emission of a Goldstone boson to the (non-relativistic) Lorentz boost of the hard scattering amplitudes. This is the on-shell avatar of the spontaneous breaking of Lorentz boosts, analogous to the Adler zero of pions in the chiral symmetry breaking. We comment on se…
We make a relativistic extension of the one-dimensional J-matrix method of scattering. The relativistic potential matrix is a combination of vector, scalar, and pseudo-scalar components. These are non-singular short-range potential functions (not necessarily analytic) such that they are well represented by their matrix elements in a finite subset of a square integrable basis set that supports a tridiagonal symmetric matrix representation for the free Dirac operator. Transmission and reflection coefficients are calculated for different potential coupling modes. This is the first of a two-paper …
We propose a non-oscillatory no-scale supergravity model of inflation (NO-NO inflation) in which the inflaton does not oscillate at the end of the inflationary era. Instead, the Universe is then dominated by the inflaton kinetic energy density (kination). During the transition from inflation to kination, the Universe preheats instantly through a coupling to Higgs-like fields. These rapidly annihilate and scatter into ultra-relativistic matter particles, which subsequently dominate the energy density, and reheating occurs at a temperature far above that of Big Bang Nucleosynthesis. After the el…
With the growing consensus on simple power law inflation models not being favored by the PLANCK observations, dynamics for the non-standard inflation gain significant interest in the recent past. In this paper, we analyze in detail a class of supergravity inspired phenomenological inflationary models with non-polynomial potential based on Maity (Nucl.Phys. B919 (2017) 560), and compare the model predictions with the currently most favored Starobinsky and its generalized $α$-attractor models in the ($n_s$ , $r$) plane constrained by PLANCK. Importantly for a wide range of parameter space, our m…
Using the consistency relation in Fourier space, we derive the observed galaxy bispectrum from single-field inflation in the squeezed limit, in which one of the three modes has a wavelength much longer than the other two. This provides a non-trivial check of the full computation of the bispectrum based on second-order cosmological perturbation theory in this limit. We show that gauge modes need to be carefully removed in the second-order cosmological perturbations in order to calculate the observed galaxy bispectrum in the squeezed limit. We then give an estimate of the effective non-Gaussiani…
Orthogonal non-Gaussianities from Dirac-Born-Infeld Galileon inflation
研究了在Dirac Born Infeld作用量中加入诱导引力项的多场相对论Galileon模型的宇宙学。我们强调的物理洞察力，是通过采用一个双度量的角度来看，其中的诱导引力和爱因斯坦-希尔伯特行动被平等对待。我们推导出条件下，准指数膨胀阶段可以持续，并证明存在一个临界背景能量密度以上的宇宙学波动成为鬼。在非线性层面上，这个场景提供了第一个具体的早期宇宙模型，其中双谱的形状可以主要是正交类型。更一般地说，我们表明，原始的非高斯性的形状和符号作为强大的判别式的精确强度的诱导引力。
The Universe is not just cold dark matter and dark energy, it also contains baryons, radiation and neutrinos. The presence of these components, beyond the pressure-less cold dark matter and the quasi-uniform dark energy ones, imply that the single clock assumption from inflation is no longer preserved. Here we quantify this effect and show that the single-clock symmetry is ensured only on scales where baryonic effects, neutrinos effects, or sound speed are zero. These scales depend on the cosmic epoch and the Universe composition. Hence for all use and purposes of interpreting state-of-the-art…
We consider a family of classical elliptic integrable systems including (relativistic) tops and their matrix extensions of different types. These models can be obtained from the "off-shell" Lax pairs, which do not satisfy the Lax equations in general case but become true Lax pairs under various conditions (reductions). At the level of the off-shell Lax matrix there is a natural symmetry between the spectral parameter $z$ and relativistic parameter $η$. It is generated by the finite Fourier transformation, which we describe in detail. The symmetry allows to consider $z$ and $η$ on an equal foot…
We study scalar particle decay during the radiation and matter dominated epochs of a standard cosmological model. An adiabatic approximation is introduced that is valid for degrees of freedom with typical wavelengths much smaller than the particle horizon ($\propto$~Hubble radius) at a given time. We implement a non-perturbative method that includes the cosmological expansion and obtain a cosmological Fermi's Golden Rule that enables one to compute the decay law of a parent particle of mass $m_1$, along with the build up of the population of daughter particles of mass $m_2$. The survival proba…
